Aero Helmet or speed suit

A lot of things can impact this, but in general, I would rank them in this order:

1) Proper fit on bike

2) Proper fitting Aero Helmet

3) Aero Wheels

4) Other Aero improvements on you and the bike (hydration, shoe covers, speed suit, etc)

What do you mean by speed suit?  Trisuit or something you use for TT's?  If the later, not sure you want to use one for a triathlon.  These are generally used for TT's and some bike races.  Not something I would want to run in.

I'm thinking a swimming speedsuit is what's meant here. Not a TT skinsuit. The TT skinsuit would be ridiculous to use for a tri.

I'd look at wetsuit over either, then helmet, then swimskin if you can't use a wetsuit.

yes, i am referring to a swimming speed suit.  The race will not be wet-suit legal so it is either a swim skin (speed suit) or an aero helmet.  

I'm also not trying to be an a$$, but a swimming lesson with a coach who can fix your position would probably cost less than either and could knock a few minutes off your swim time (depending upon event length). It may even knock off more than the speed suit depending on how ingrained your habits are.

a few more details:  i have a swim coach, and I am comfortable with my speed/hours trained in the pool.  I also have a tri bike that fits comfortable, and has been properly fitted.   If i had an extra $400 burning a hole in my pocket, (which i do) should i get the aero helmet or the swim skin?  which one will have the greatest affect on my overall time.  How much time will a swim skin shave off versus an aero helemt.

Although if i swam with the areo helmet it might make me more buoyant?!?! No?

$400 could probably get both? I just got an giro advantage ii for 110, and I think a you can probably get a skin for $200-300.

2:30 per 100m is pretty low hanging fruit though in terms of improving your swim with more training.

You absolutely can get both for under $400. Something's not right otherwise.

Curious how long ago you started swimming, when the event is, and things like that. With 2:30/100 pacing, then you will almost certainly save more time figuring out how to swim better than anywhere else. And since it's an IM do not underestimate much energy that will save you for the other two (by not swimming for as long), thereby increasing your overall time further. Even if you take it easy in the swim, it's going to be a very significant energy drain that will show up later in the day. From this speed, it can be more than any gear improvements.

I hope this doesn't sound pushy, but rather to encourage to take a good, honest look at how swimming is progressing.

What exactly do you mean by "full distance triathlon"?  A full Ironman?

Are your logs accurate and up to date? 

With alll due respect, you've got a lot more to gain by training more than do by throwing money at gear.  While neither is going to make you slower, it would be hard to actually measure any improvement directly attributable to either a helmet or skin suit (I assume you're talking about a one-piece tri suit). 

Regardless, it's your money, so you can spend it any way you want to.  Again, the commonly held opinion is that an aero helmet gives you the most "bang for the buck".

FWIW, I got a Giro Advantage II aero helmet in the middle of last year and wore it for my last couple of races (both sprints 12.5 & 14.0 miles).  Didn't see any significant improvement in my times.  Too many other variables in the equation: course, road condition, temperature, wind, my condition, etc. 

Good luck

Mark

Actually I will disagree with that.  In the pool I am about 1:55-1:58/100m (on a 500m test, haven't tried a 100m all out).  Ended up getting a swimskin pretty cheap.  It did help and will continue to wear it.  Definitely felt like I was gliding thru the water.  Placebo?  Doubt it but its a possibility but I will wear the swimskin in any OWS that is not wetsuit legal.

Once again I think that's why the swim is such a huge factor-so much to gain there with out too much extra physical effort. I frequently see swimmers at the pool that look like they struggled to walk across the parking lot but can swim consistently fast smooth laps with good form.

My understanding of aero helmets is that you must be able to hold your aero position to get the full benefit, otherwise, I assume, they create more drag than they save.

To help you out, look to get better than 2:00/100 or so. Now you have a very obtainable goal to shoot for that will make a significant difference in how the day goes. After that it can be more debatable on where your focus should be.

How much did it help? And keep in mind that he said "not that much", not "not at all".

Going back to OP's specific question of which will save more time all things being equal.  I'd estimate based on my own experience that the speedsuit would save about 2-3 seconds per 100.  This equates to 1:30 to 2:00.  The speedsuit shouldn't take more than 15 seconds to remove.  So to be generous I'd just estimate a 2 minute savings.

For the aero helmet, I've read estimates of three to six minutes savings for a full IM.  So purely to answer your question those are the best numbers I can think of.

For what will probably be a 15 hour effort or so though, I think that even six minutes will not make any difference on the day.  If it were me, I'd spend the extra on the celebration afterwards.

DING! DING! DING! we have a winner! Thank you!  That is the information i was looking for! thank you very much!  

For The Win!!!

Train more, swim more, yada, yada, yada.  After all that training, you still got $400 left in your pocket.

Get an aero helmet.  Look around and you can usually get one under $100.  That should save you at least a few minutes over an IM.

Spend another $125 on some good racing tires and latex tubes.  Depending on what you're running now...that can save you another 5-10 minutes.  I prefer the Vittoria Open Corsa Evo CX tires and Challenge latex tubes.

Take the other $175 and buy some more beer.

A swim skin will not provide you with the full benefits until you are much faster on the swim. Poor body position/technique can't be overcome with a slick suit. Coat a potato in teflon and it won't be more hydrodynamic either. You might gain some time on an IM swim, but the hassle of removing the suit for the bike portion will eat into that as well. (and yes, I know it should only take seconds to remove, but sometimes things get stuck and any distraction at IM is magnified)

Worn properly and in conjunction with a good aero position on a tri bike, you will get a better benefit from an aero helmet, but again, your speed is low enough (16mph you said) that the gains won't be significant. 

If you are really maxing out your potential (which I doubt, but that is another thread) then I might suggest that you skip the neck cramp inducing aero helmet and feel better on the run which might actually gain you more time. If a swim skin makes you happy then get one. 

Note that I say all this as a) someone who sells "free speed" for a living in the form of tri apparel, wetsuits, etc and b) someone who is probably too slow to see the benefits of an aero helmet or swim skin either.

-Joey
US Sales Rocket Science Sports
www.RocketScienceSports.com